This invention relates to oxazolo, thiazolo and selenazolo [4,5-c]-quinolin-, tetrahydroquinolin-4-amines and hetero analogs thereof, and to intermediates used in their preparation. The invention also relates to pharmaceutical compositions containing the above compounds as well as the use of these compounds as immunomodulators and for inducing cytokine biosynthesis, including interferon-xcex1 biosynthesis and/or tumor necrosis factor-xcex1 biosynthesis.
The first reliable report on the 1H-imidazo[4,5-c]quinoline ring system, Backman et al., J. Org. Chem. 15, 1278-1284 (1950) describes the synthesis of 1-(6-methoxy-8-quinolinyl)-2-methyl-1H-imidazo[4,5-c]quinoline for possible use as an antimalarial agent. Subsequently, syntheses of various substituted 1H-imidazo[4,5-c] quinolines have been reported. For example, Jain et al., J. Med. Chem. 11, pp. 87-92 (1968), has synthesized the compound 1-[2-(4-piperidyl)ethyl]-1H-imidazo[4,5-c]quinoline as a possible anticonvulsant and cardiovascular agent. Also, Baranov et al., Chem. Abs. 85, 94362 (1976), and Berenyi et al., J. Heterocyclic Chem. 18, 1537-1540 (1981), have reported certain 2-oxoimidazo[4,5-c]quinolines.
Following the above report, 1H-imidazo[4,5-c]quinolin-4-amines and 1- and 2-substituted derivatives thereof were found to be useful as antiviral agents, bronchodilators and immunomodulators. These are described in U.S. Pat. Nos. 4,689,338; 4,698,348; 4,929,624; 5,037,986; 5,266,675; 5,268,376; 5,346,905; 5,389,640; 5,605,899; 5,352,784; 5,446,153; and 5,482,936. Shen et al., U.S. Pat. Nos. 4,038,396 and 4,131,677, describe certain oxazolo-and thiazolopyridines as having antiinflammatory, analgesic, and antipyretic properties.
The present invention provides compounds of the Formula I 
wherein:
R1 is selected from the group consisting of oxygen, sulfur and selenium;
R2 is selected from the group consisting of
-hydrogen;
-alkyl;
-alkyl-OH;
-haloalkyl;
-alkenyl;
-alkyl-X-alkyl;
-alkyl-X-alkenyl;
-alkenyl-X-alkyl;
-alkenyl-X-alkenyl;
-alkyl-N(R5)2;
-alkyl-N3;
-alkyl-O-C(O)-N(R5)2;
-heterocyclyl;
-alkyl-X-heterocyclyl;
-alkenyl-X-heterocyclyl;
-aryl;
-alkyl-X-aryl;
-alkenyl-X-aryl;
-heteroaryl;
-alkyl-X-heteroaryl; and
-alkenyl-X-heteroaryl;
R3 and R4 are each independently:
-hydrogen;
-X-alkyl;
-halo;
-haloalkyl;
-N(R5)2;
or when taken together, R3 and R4 form a fused aromatic, heteroaromatic, cycloalkyl or heterocyclic ring;
X is selected from the group consisting of xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NR5xe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94C(O)Oxe2x80x94, xe2x80x94OC(O)xe2x80x94, and a bond; and
each R5 is independently H or C1-8alkyl;
with the proviso that when R1 is sulfur, R3 is not xe2x80x94NH2; or a pharmaceutically acceptable salt thereof.
As a second aspect, the present invention provides pharmaceutical compositions containing a therapeutically effective amount of a compound of Formula I(a) and a pharmaceutically acceptable vehicle: 
wherein:
R1 is selected from the group consisting of oxygen, sulfur and selenium;
R2 is selected from the group consisting of
-hydrogen;
-alkyl;
-alkyl-OH;
-haloalkyl;
-alkenyl;
-alkyl-X-alkyl;
-alkyl-X-alkenyl;
-alkenyl-X-alkyl;
-alkenyl-X-alkenyl;
-alkyl-N(R5)2;
-alkyl-N3;
-alkyl-O-C(O)-N(R5)2;
-heterocyclyl;
-alkyl-X-heterocyclyl;
-alkenyl-X-heterocyclyl;
-aryl;
-alkyl-X-aryl;
-alkenyl-X-aryl;
-heteroaryl;
-alkyl-X-heteroaryl; and
-alkenyl-X-heteroaryl;
R3 and R4 are each independently:
-hydrogen;
-X-alkyl;
-halo;
-haloalkyl;
-N(R5)2;
or when taken together, R3 and R4 form a fused aromatic, heteroaromatic, cycloalkyl or heterocyclic ring;
X is selected from the group consisting of xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NR5xe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94C(O)Oxe2x80x94, xe2x80x94OC(O)xe2x80x94, and a bond; and
each R5 is independently H or C1-8alkyl;
or a pharmaceutically acceptable salt thereof.
The compounds of Formula I(a) are useful in inducing the biosynthesis of certain cytokines in animals, including humans. Cytokines that may be induced by the compounds of the invention include but are not limited to, interferons, particularly interferon-xcex1, and tumor necrosis factor-xcex1. The invention therefore also provides a method of inducing cytokine biosynthesis in an animal by administering to the animal an effective amount of a composition comprising a compound of Formula I(a). Because of their ability to induce cytokine biosynthesis the compounds of the invention are useful in the treatment of a variety of conditions, including viral and neoplastic diseases, and the invention further provides a method of treating such conditions in a subject by administering a therapeutically effective amount of a composition comprising a compound of Formula I(a) to the subject.
As yet another aspect, the present invention provides intermediate compounds of Formula II 
wherein:
R1 is selected from the group consisting of oxygen, sulfur and selenium;
R2 is selected from the group consisting of
-hydrogen;
-alkyl;
-alkyl-OH;
-haloalkyl;
-alkenyl;
-alkyl-X-alkyl;
-alkyl-X-alkenyl;
-alkenyl-X-alkyl;
-alkenyl-X-alkenyl;
-alkyl-N(R5)2;
-alkyl-N3;
-alkyl-O-C(O)-N(R5)2;
-heterocyclyl;
-alkyl-X-heterocyclyl;
-alkenyl-X-heterocyclyl;
-aryl;
-alkyl-X-aryl;
-alkenyl-X-aryl;
-heteroaryl;
-alkyl-X-heteroaryl;
-alkenyl-X-heteroaryl;
-SO2CH3; and
-CH2-O-C(O)-CH3;
R3 and R4 are each independently:
-hydrogen;
-X-alkyl;
-halo;
-haloalkyl;
-N(R5)2;
or when taken together, R3 and R4 form a fused aromatic, heteroaromatic, cycloalkyl or heterocyclic ring;
X is selected from the group consisting of xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NR5xe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94C(O)Oxe2x80x94, and a bond; and
each R5 is independently H or C1-8alkyl.
This invention includes compounds of Formula I, pharmaceutical compositions containing compounds of Formula I(a) and therapeutic methods using compounds of Formula I(a) as well as intermediate compounds of Formula II that are used to prepare the compounds of Formulae I and I(a).
The terms xe2x80x9calkylxe2x80x9d and xe2x80x9calkenylxe2x80x9d as used herein refer to a straight or branched hydrocarbon group, or a cyclic group (i.e., cycloalkyl and cycloalkenyl) that contains from 1 to 20, preferably 1 to 10, more preferably 1 to 8 carbon atoms, unless otherwise specified. Typical alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. Exemplary cyclic groups include cyclopropyl, cyclopentyl, cyclohexyl, cyclohexenyl and adamantyl. The prefix xe2x80x9calk,xe2x80x9d when used, e.g. for xe2x80x9calkoxyxe2x80x9d and the like, also has the same meaning.
The term xe2x80x9carylxe2x80x9d refers to a carbocyclic aromatic ring or ring system. The aryl group is preferably a six-membered ring, such as phenyl, or an aromatic polycyclic ring system, such as naphthyl. The most preferred aryl group is phenyl which may be unsubstituted or substituted by one or more substituents as defined below. Examples of other suitable aryl groups include biphenyl, fluorenyl and indenyl.
The term xe2x80x9cheteroarylxe2x80x9d refers to an aromatic ring or ring system that contains one or more heteroatoms, in which the heteroatoms are selected from nitrogen, oxygen and sulfur. Suitable heteroaryl groups include furyl, thienyl, pyridyl, quinolinyl, tetrazolyl, imidazo, and so on. In the case where R3 and R4 are taken together and form a 5- or 6-membered heteroaromatic ring, the heteroatom is nitrogen, oxygen or sulfur and the ring may contain one or more of such atoms. Preferably, the heteroatom is nitrogen or sulfur. Preferred heteroaromatic rings formed by R3 and R4 are illustrated by the following formulae where the two lines indicate where they are fused. 
The terms xe2x80x9cheterocyclicxe2x80x9d and xe2x80x9cheterocyclylxe2x80x9d refer to non-aromatic rings or ring systems that contain one or more ring heteroatoms (e.g., O, S, N). Exemplary heterocyclic groups include pyrrolidinyl, tetrahydrofuranyl, morpholinyl, piperidino, piperazino, thiazolidinyl, imidazolidinyl, and the like.
All of the above rings and ring systems can be unsubstituted or substituted by one or more substituents selected from the group consisting of alkyl, alkoxy, alkylthio, hydroxy, halogen, haloalkyl, polyhaloalkyl, perhaloalkyl (e.g., trifluoromethyl), trifluoroalkoxy (e.g., trifluoromethoxy), nitro, amino, alkylamino, dialkylamino, alkylcarbonyl, alkenylcarbonyl, arylcarbonyl, heteroarylcarbonyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, heterocyclyl, heterocycloalkyl, nitrile and alkoxycarbonyl. Preferred substituents are C1-4 alkyl, C1-4 alkoxy, halo, amino, alkylamino, dialkylamino, hydroxy, C1-4 alkoxymethyl and trifluoromethyl.
The term xe2x80x9chaloxe2x80x9d refers to a halogen atom, such as, for example, fluorine, chlorine, bromine or iodine.
The invention is inclusive of the compounds described herein in any of their pharmaceutically acceptable forms, including isomers such as diastereomers and enantiomers, salts, solvates, polymorphs and the like.
As noted above, the compounds of Formula I and I(a) are capable of forming xe2x80x9cpharmaceutically acceptable salt(s).xe2x80x9d Pharmaceutically acceptable acid addition salts of the compounds of Formula I and I(a) include salts derived from nontoxic inorganic acids such as hydrochloric, nitric, phosphoric, sulfuric, hydrobromic, hydriodic, hydrofluoric, phosphorous, and the like, as well as the salts derived from nontoxic organic acids, such as aliphatic mono- and dicarboxylic acids, phenyl-substituted alkanoic acids, hydroxy alkanoic acids, alkanedioic acids, aromatic acids, aliphatic and aromatic sulfonic acids, etc. Such salts thus include sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, nitrate, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, trifluoroacetate, propionate, caprylate, isobutyrate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, mandelate, benzoate, chlorobenzoate, methylbenzoate, hydroxynaphthoate, xinafoate, dinitrobenzoate, phthalate, benzenesulfonate, toluenesulfonate, phenylacetate, citrate, lactate, maleate, tartrate, methanesulfonate, and the like. Also contemplated are salts of amino acids such as arginate and the like and gluconate, galacturonate (see, for example, Berge S M, et al., xe2x80x9cPharmaceutical Salts,xe2x80x9d J. Pharm. Sci. 1977;66:1).
The acid addition salts of the compounds are prepared by contacting the free base form with a sufficient amount of the desired acid to produce the salt in the conventional manner. The free base form may be regenerated by contacting the salt form with a base and isolating the free base in the conventional manner.
Preferred compounds of Formula I and I(a) are those wherein R1 is oxygen or sulfur. Preferred R2 substituents include alkyl and alkoxyalkyl, with C1-4 alkyl especially preferred.
It is preferred that R3 and R4 be taken together to form a fused benzene or pyridine ring that may be substituted or unsubstituted.
Most preferred compounds are those of the Formula III or IV 
wherein R2 is defined above, and R is hydrogen, alkyl, alkoxy, alkylthio, hydroxy, halogen, haloalkyl, polyhaloalkyl, perhaloalkyl (e.g., trifluoromethyl), trifluoroalkoxy (e.g., trifluoromethoxy), nitro, amino, alkylamino, dialkylamino, alkylcarbonyl, alkenylcarbonyl, arylcarbonyl, heteroarylcarbonyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, heterocyclyl, heterocycloalkyl, nitrile and alkoxycarbonyl.
Exemplary Compounds of the Invention Include:
2-methylthiazolo[4,5-c]quinolin-4-amine;
thiazolo[4,5-c]quinolin-4-amine;
2-ethylthiazolo[4,5-c]quinolin-4-amine;
2-propylthiazolo[4,5-c]quinolin-4-amine;
2-pentylthiazolo[4,5-c]quinolin-4-amine;
2-butylthiazolo[4,5-c]quinolin-4-amine;
2-(1-methylethyl)thiazolo[4,5-c]quinolin-4-amine;
2-(2-phenyl-1-ethenyl)thiazolo[4,5-c]quinolin-4-amine;
2-(2-phenyl-1-ethyl)thiazolo[4,5-c]quinolin-4-amine;
2-(4-aminothiazolo[4,5-c]quinolin-2-yl)-1,1-dimethylethyl carbamate;
2-(ethoxymethyl)thiazolo[4,5-c]quinolin-4-amine;
2-(methoxymethyl)thiazolo[4,5-c]quinolin-4-amine;
2-(2-methylpropyl)thiazolo[4,5-c]quinolin-4-amine;
2-benzylthiazolo[4,5-c]quinolin-4-amine;
8-methyl-2-propylthiazolo[4,5-c]quinolin-4-amine;
(4-aminothiazolo[4,5-c]quinolin-2-yl)methanol;
2-methyloxazolo[4,5-c]quinolin-4-amine;
2-ethyloxazolo[4,5-c]quinolin-4-amine;
2-butyloxazolo[4,5-c]quinolin-4-amine;
2-propylthiazolo [4,5-c] quinolin-4,8-diamine;
2-propyloxazolo [4,5-c] quinolin-4-amine;
8-bromo-2-propylthiazolo[4,5-c]quinolin-4-amine;
7-methyl-2-propylthiazolo[4,5-c]quinolin-4-amine;
2-butyl-7-methyloxazolo[4,5-c]quinolin-4-amine;
7-methyl-2-propyloxazolo[4,5-c]quinolin-4-amine;
7-fluoro-2-propyloxazolo [4,5-c]quinolin-4-amine;
7-fluoro-2-propylthiazolo[4,5-c]quinolin-4-amine;
2-propyl-7-(trifluoromethyl)thiazolo[4,5-c]quinolin-4-amine;
2-(4-morpholino)thiazolo[4,5-c]quinolin-4-amine;
2-(1-pyrrolidino)thiazolo[4,5-c]quinolin-4-amine;
2-butylthiazolo[4,5-c] [1,5]naphthyridin-4-amine;
2-propylthiazolo[4,5-c] [1,5]naphthyridin-4-amine;
7-chloro-2-propylthiazolo[4,5-c]quinolin-4-amine;
7-methoxy-2-propylthiazolo[4,5-c]quinolin-4-amine;
and pharmaceutically acceptable salts thereof, particularly the hydrochloride salts thereof.
Preparation of the Compounds
Compounds of the invention can be prepared according to Reaction Scheme I wherein R1, R2, R3 and R4 are as defined above.
In step (1) of Reaction Scheme I a compound of Formula V is reacted with a carboxylic acid or an equivalent thereof to provide a compound of Formula VI. Suitable equivalents to carboxylic acid include acid anhydrides, acid chlorides, orthoesters and 1,1-dialkoxyalkanoates. The carboxylic acid or equivalent is selected such that it will provide the desired R2 substituent in a compound of Formula VI. For example, triethyl orthoformate will provide a compound of Formula VI where R2 is hydrogen and acetic anhydride will provide a compound of Formula VI where R2 is methyl. The reaction can be run in the absence of solvent, in the presence of an acid such as polyphosphoric acid, or preferably in the presence of a carboxylic acid of the formula R2C(O)OH. The reaction is run with sufficient heating to drive off any alcohol or water formed as a byproduct of the reaction. The compounds of Formula V are known or may be prepared using conventional methods (see for example, Bachman et. al., Journal of the American Chemical Society, 69, pp 365-371 (1947); Ambrogi et. al., Synthesis, pp. 656-658 (1992); Adler et. al., Journal of the Chemical Society, pp.1794-1797 (1960); Sxc3xcs et. al., Justus Liebigs Annalen der Chemie, 583, pp. 150-160 (1953); and Sxc3xcs et. al., Justus Liebigs Annalen der Chemie, 593, pp. 91-126 (1955).
In step (2) of Reaction Scheme I a compound of Formula VI is oxidized to provide an N-oxide of Formula II. The oxidation is carried out using a conventional oxidizing agent that is capable of forming N-oxides. Preferred reaction conditions involve reacting a solution of a compound of Formula VI in chloroform with 3-chloroperoxybenzoic acid at ambient conditions. Alternatively the oxidation may be carried out using peracetic acid in a suitable solvent such as ethyl or methyl acetate.
In step (3) of Reaction Scheme I an N-oxide of Formula II is aminated to provide a compound of Formula I. Step (3) involves (i) reacting a compound of Formula II with an acylating agent and then (ii) reacting the product with an aminating agent. Part (i) of step (3) involves reacting an N-oxide of Formula II with an acylating agent. Suitable acylating agents include alkyl- or arylsulfonyl chlorides (e.g., benezenesulfonyl chloride, methanesulfonyl chloride, p-toluenesulfonyl chloride). Arylsulfonyl chlorides are preferred. Para-toluenesulfonyl chloride is most preferred. Part (ii) of step (3) involves reacting the product of part (i) with an excess of an aminating agent. Suitable aminating agents include ammonia (e.g., in the form of ammonium hydroxide) and ammonium salts (e.g., ammonium carbonate, ammonium bicarbonate, ammonium phosphate). Ammonium hydroxide is preferred. The reaction is preferably carried out by dissolving or suspending the N-oxide of Formula II in an inert solvent such as dichloromethane or chloroform, adding the aminating agent to the solution or suspension, and then slowly adding the acylating agent. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods.
Alternatively, step (3) can be carried out by (i) reacting an N-oxide of Formula II with an isocyanate and then (ii) hydrolyzing the resulting product. Part (i) involves reacting the N-oxide with an isocyanate wherein the isocyanato group is bonded to a carbonyl group. Preferred isocyanates include trichloroacetyl isocyanante and aroyl isocyanates such as benzoyl isocyanate. The reaction of the isocyanate with the N-oxide is carried out under substantially anhydrous conditions by adding the isocyanate to a solution of the N-oxide in an inert solvent such as dichloromethane. Part (ii) involves hydrolysis of the product from part (i). The hydrolysis can be carried out by conventional methods such as heating in the presence of water or a lower alkanol optionally in the presence of a catalyst such as an alkali metal lower alkoxide or ammonia. 
Compounds of the invention wherein R1 is oxygen or sulfur and R3 and R4 together form an optionally substituted aromatic ring can be prepared according to Reaction Scheme II wherein R and R2 are as defined above.
In step (1) of Reaction Scheme II a 3-aminoquinolin-4-ol or 3-aminoquinolin-4-thiol of Formula VII is reacted with a carboxylic acid or an equivalent thereof to provide an oxazolo- or thiazolo[4,5-c]quinoline of Formula VIII. Suitable equivalents to carboxylic acid include acid anhydrides, acid chlorides, orthoesters and 1,1-dialkoxyalkanoates. The carboxylic acid or equivalent is selected such that it will provide the desired R2 substituent in a compound of Formula VIII. For example, triethyl orthoformate will provide a compound of Formula VIII where R2 is hydrogen and acetic anhydride will provide a compound of Formula VIII where R2 is methyl. The reaction can be run in the absence of solvent, in the presence of an acid such as polyphosphoric acid, or preferably in the presence of a carboxylic acid of the formula R2C(O)OH. The reaction is run with sufficient heating to drive off any alcohol or water formed as a byproduct of the reaction. The 3-aminoquinolin-4-ols and 3-aminoquinolin-4-thiols of Formula VII are known or may be prepared using known methods.
In step (2) of Reaction Scheme II an oxazolo- or thiazolo[4,5-c]quinoline of Formula VIII is oxidized to provide an oxazolo- or thiazolo[4,5-c]quinolin-5N-oxide of Formula IX which is a subgenus of Formula II. The oxidation is carried out using a conventional oxidizing agent that is capable of forming N-oxides. Preferred reaction conditions involve reacting a solution of a compound of Formula VIII in chloroform with 3-chloroperoxybenzoic acid at ambient conditions. Alternatively the oxidation may be carried out using peracetic acid in a suitable solvent such as ethyl or methyl acetate.
In step (3) of Reaction Scheme II an N-oxide of Formula IX is aminated to provide an oxazolo[4,5-c]quinolin-4-amine of Formula III or a thiazolo[4,5-c]quinolin-4-amine of Formula IV both of which are subgenera of Formula I. Step (3) involves (i) reacting a compound of Formula IX with an acylating agent and then (ii) reacting the product with an aminating agent. Part (i) of step (3) involves reacting an N-oxide of Formula IX with an acylating agent. Suitable acylating agents include alkyl- or arylsulfonyl chlorides (e.g., benezenesulfonyl chloride, methanesulfonyl chloride, p-toluenesulfonyl chloride). Arylsulfonyl chlorides are preferred. Para-toluenesulfonyl chloride is most preferred. Part (ii) of step (3) involves reacting the product of part (i) with an excess of an aminating agent. Suitable aminating agents include ammonia (e.g., in the form of ammonium hydroxide) and ammonium salts (e.g., ammonium carbonate, ammonium bicarbonate, ammonium phosphate). Ammonium hydroxide is preferred. The reaction is preferably carried out by dissolving or suspending the N-oxide of Formula IX in an inert solvent such as dichloromethane or chloroform, adding the aminating agent to the solution or suspension, and then slowly adding the acylating agent. The product or a pharmaceutically acceptable salt thereof can be isolated using conventional methods.
Alternatively, step (3) can be carried out by (i) reacting an N-oxide of Formula IX with an isocyanate and then (ii) hydrolyzing the resulting product. Part (i) involves reacting the N-oxide with an isocyanate wherein the isocyanato group is bonded to a carbonyl group. Preferred isocyanates include trichloroacetyl isocyanante and aroyl isocyanates such as benzoyl isocyanate. The reaction of the isocyanate with the N-oxide is carried out under substantially anhydrous conditions by adding the isocyanate to a solution of the N-oxide in an inert solvent such as dichloromethane. Part (ii) involves hydrolysis of the product from part (i). The hydrolysis can be carried out by conventional methods such as heating in the presence of water or a lower alkanol optionally in the presence of a catalyst such as an alkali metal lower alkoxide or ammonia. 
Compounds of the invention wherein R1 is sulfur can also be prepared according to Reaction Scheme III wherein R2, R3 and R4 are as defined above.
In step (1) of Reaction Scheme III a compound of Formula X is reacted with an acyl halide of formula R2C(O)Z wherein R2 is as defined above and Z is chloro or bromo to provide an amide of Formula XI. The reaction can be carried out by adding the acyl halide in a controlled fashion (e.g., dropwise) to a solution or suspension of a compound of Formula X in a suitable solvent such as pyridine or dichloromethane in the presence of a tertiary amine.
In step (2) of Reaction Scheme III an amide of Formula XI is reacted with phosphorous pentasulfide to provide a compound of Formula XII. The reaction can be carried out by adding phosphorous pentasulfide to a solution or suspension of a compound of Formula XI in a suitable solvent such as pyridine and heating the resulting mixture.
Steps (3) and (4) of Reaction Scheme III can be carried out in the same manner as steps (2) and (3) of Reaction Scheme I respectively to provide an N-oxide of Formula XIII which is a subgenus of Formula II and a compound of Formula XIV which is a subgenus of Formula I respectively. 
Compounds of the invention wherein R1 is sulfur and R3 and R4 together form an optionally substituted aromatic ring can also be prepared according to Reaction Scheme IV wherein R and R2 are as defined above.
In step (1) of Reaction Scheme IV a 3-aminoquinolin-4-ol of Formula XV is reacted with an acyl halide of formula R2C(O)Z wherein R2 is as defined above and Z is chloro or bromo to provide an N-(4-hydroxyquinolin-3-yl)amide of Formula XVI. The reaction can be carried out by adding the acyl halide in a controlled fashion (e.g., dropwise) to a solution or suspension of a compound of Formula XV in a suitable solvent such as dichloromethane in the presence of a tertiary amine.
In step (2) of Reaction Scheme IV an N-(4-hydroxyquinolin-3-yl)amide of Formula XVI is reacted with phosphorous pentasulfide to provide a thiazolo[4,5-c]quinoline of Formula XVII. The reaction can be carried out by adding phosphorous pentasulfide to a solution or suspension of a compound of Formula XVI in a suitable solvent such as pyridine and heating the resulting mixture.
Steps (3) and (4) of Reaction Scheme IV can be carried out in the same manner as steps (2) and (3) of Reaction Scheme II respectively to provide a thiazolo[4,5-c]quinolin-5N-oxide of Formula XVIII which is a subgenus of Formula II and a thiazolo[4,5-c]quinolin-4-amine of Formula IV which is a subgenus of Formula I respectively. 
Substituents at the 2-position can be introduced by reacting a compound of Formula XIX 
wherein R1 is oxygen or sulfur and R is as defined above, with a lithiating agent such as lithium diisopropylamide or n-butyllithium in a polar aprotic solvent to provide a compound lithiated on the 2-methyl group. The lithiated compound can then be reacted with an appropriate reagent containing a leaving group capable of being displaced by the lithiated 2-methyl group. Examples of suitable reagents include halides such as methyl iodide or chloromethylmethylether, aldehydes such as benzaldehyde, and ketones such as acetone. The compounds can then be oxidized and aminated using the methods described above to provide compounds of Formulas III or IV.
Some compounds of Formula I may be prepared directly from other compounds of Formula I. For example, nitration of 2-propylthiazolo[4,5-c]quinolin-4-amine provides 8-nitro-2-propylthiazolo[4,5-c]quinolin-4-amine and the reduction of the nitro compound provides 2-propylthiazolo[4,5-c]quinoline-4,8-diamine.
Pharmaceutical Compositions and Biological Activity
Pharmaceutical compositions of the invention contain a therapeutically effective amount of a compound of Formula I(a) together with a pharmaceutically acceptable carrier.
As used herein, the term xe2x80x9ca therapeutically effective amountxe2x80x9d means an amount of the compound sufficient to induce a desired therapeutic effect, such as cytokine biosynthesis, antitumor activity and/or antiviral activity. Although the exact amount of active compound used in a pharmaceutical composition of the invention will vary according to factors known to those of skill in the art, such as the physical and chemical nature of the compound as well as the nature of the carrier, the intended dosing regimen and the condition to be treated, it is anticipated that the compositions of the invention will contain sufficient active ingredient to provide a dose of about 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg of the compound to the subject. Any of the conventional dosage forms may be used, such as tablets, lozenges, parenteral formulations, syrups, creams, ointments, aerosol formulations, transdermal patches, transmucosal patches and so on. The dosage form used will also depend on the characteristics of the compound to be administered. For example, certain compounds of Formula I(a), especially those wherein R1 is sulfur, tend to have relatively low oral bioavailability and are rapidly metabolized when they enter the bloodstream. These properties make such compounds particularly well suited for treatment of conditions where topical administration of an immune response modifying compound is desirable, such as asthma, basal cell carcinoma, cervical intraepithelial neoplasia and so on.
The compounds of the invention have been shown to induce the production of certain cytokines in experiments performed according to the Test Method set forth below. These results indicate that the compounds are useful as immune response modifiers that can modulate the immune response in a number of different ways, rendering them useful in the treatment of a variety of disorders.
Cytokines that are induced by the administration of compounds according to the invention generally include interferon-xcex1 (IFN-xcex1) and/or tumor necrosis factor-xcex1 (TNF-xcex1) as well as certain interleukins (IL). Cytokines whose biosynthesis may be induced by compounds of the invention include IFN-xcex1, TNF-xcex1, IL-1, 6, 10 and 12, and a variety of other cytokines. Among other effects, cytokines inhibit virus production and tumor cell growth, making the compounds useful in the treatment of tumors and viral diseases.
In addition to the ability to induce the production of cytokines, the compounds of the invention affect other aspects of the innate immune response. For example, natural killer cell activity may be stimulated, which effect may be due to cytokine induction. The compounds may also activate macrophages, which in turn stimulates secretion of nitric oxide and the production of additional cytokines. Further, the compounds may cause proliferation and differentiation of B-lymphocytes and may be useful in the in vitro maturation of dendritic cells.
Compounds of the invention also have an effect on the acquired immune response. For example, although there is not believed to be any direct effect on T cells or direct induction of T cell cytokines, the production of the T helper type 1 (Th1) cytokine IFN-xcex3 is induced indirectly and the production of the T helper type 2 (Th2) cytokines 1L-4, IL-5 and IL-13 are inhibited upon administration of the compounds. This activity means that the compounds are useful in the treatment of diseases where upregulation of the Th1 response and/or down regulation of the Th2 response is desired. In view of the ability of compounds of Formula Ia to inhibit the Th2 immune response, the compounds are expected to be useful in the treatment of atopy, e.g., atopic dermatitis, asthma, allergy, allergic rhinits, and systemic lupus erythematosis; as a vaccine adjuvant for the enhancement of cell mediated immunity; and possibly as a treatment for recurrent fungal diseases and chlamydia.
The immune response modifying effects of the compounds make them useful in the treatment of a wide variety of conditions. Because of their ability to induce cytokines such as IFN-xcex1 and/or TNF-xcex1, the compounds are particularly useful in the treatment of viral diseases and tumors. This immunomodulating activity suggests that compounds of the invention are useful in treating diseases such as, but not limited to, viral diseases e.g., genital warts, common warts, plantar warts, Hepatitis B, Hepatits C, Herpes Simplex Type I and Type II, molluscum contagiosm, HIV, CMV, VZV, cervical intraepithelial neoplasia, human papillomavirus and associated neoplasias; fungal diseases, e.g., candida, aspergillus, cryptococcal meningitis; neoplastic diseases, e.g., basal cell carcinoma, hairy cell leukemia, Kaposi""s sarcoma, renal cell carcinoma, squamous cell carcinoma, myelogenous leukemia, multiple myeloma, melanoma, non-Hodgkin""s lymphoma, cutaneous T-cell lymphoma, and other cancers; parasitic diseases, e.g., pneumocystis carnii, cryptospordiosis, histoplasmosis, toxoplasmosis, trypanosome infection, leishmaniasis; and bacterial infections, e.g., tuberculosis, mycobacterium avium. Additional diseases or conditions that can be treated using the compounds of the invention include eczema, eosinophilia, essential thrombocythaemia, leprosy, multiple sclerosis, Ommen""s syndrome, rheumatoid arthritis, systemic lupus erythematosis, discoid lupus, Bowen""s disease, Bowenoid papulosis, and to enhance or stimulate the healing of wounds, including chronic wounds.
Accordingly, the invention provides a method of inducing cytokine biosynthesis in an animal comprising administering an effective amount of a compound of Formula Ia to the animal. An amount of a compound effective to induce cytokine biosynthesis is an amount sufficient to cause one or more cell types, such as monocytes, macrophages, dendritic cells and B-cells to produce an amount of one or more cytokines such as, for example, IFN-xcex1, TNF-xcex1, IL-1,6,10 and 12 that is increased over the background level of such cytokines. The precise amount will vary according to factors known in the art but is expected to be a dose of about 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg. The invention also provides a method of treating a viral infection in an animal comprising administering an effective amount of a compound of Formula Ia to the animal. An amount effective to treat or inhibit a viral infection is an amount that will cause a reduction in one or more of the manifestations of viral infection, such as viral lesions, viral load, rate of virus production, and mortality as compared to untreated control animals. The precise amount will vary according to factors known in the art but is expected to be a dose of 100 ng/kg to about 50 mg/kg, preferably about 10 xcexcg/kg to about 5 mg/kg.
Compounds of the invention may be administered to the subject as the sole therapeutic agent, or may form part of a therapeutic regimen in combination with one or more other agents. Examples of suitable agents that may be used in combination with the immune response modifying compounds of the invention include, but are not limited to, analgesics, antibacterials, antifungals, antiinflammatory agents, antitumor agents, antivirals, bronchodilators, narcotics, and steroids.
The following examples are provided to illustrate the invention, but should not be considered to be limiting in any way.